Van Asseldonk J T H, Van den Berg L H, Van den Berg-Vos R M, Wieneke G H, Wokke J H J, Franssen H
Department of Neurology, Rudolf Magnus Institute for Neurosciences, University Medical Centre Utrecht, The Netherlands.
Brain. 2003 Jan;126(Pt 1):186-98. doi: 10.1093/brain/awg019.
Multifocal motor neuropathy (MMN) is characterized by a slowly progressive, asymmetric weakness of the limbs without sensory loss. The arms are usually affected to a greater extent than the legs, and distal muscles more than proximal muscles. The distribution of electrophysiological abnormalities and its correlation with weak muscle groups in MMN have not been investigated systematically. The aim of the present study was to assess whether electrophysiological abnormalities have a preferential or random distribution, whether electrophysiological abnormalities in a nerve correlate with weakness in the innervated muscles, and whether these results are relevant for the development of optimal electrodiagnostic protocols. We compared the pattern of weakness and electrophysiological abnormalities in 39 patients with a lower motoneuron syndrome and a positive response to intravenous immunoglobulins. All patients underwent an extensive standardized electrophysiological examination. Electrophysiological evidence of demyelination was found more often in the nerves of the arms and was distributed randomly over lower arm, upper arm and shoulder segments. Electrophysiological evidence of axonal loss presented more frequently in longer nerves, occurring most often in the leg nerves. For the arm nerves, it is possible that the length dependence of axonal loss is due to the random distribution of demyelinating lesions that lead to axonal degeneration. Weakness was associated with features of demyelination and axonal loss in the nerves of the arm, and with features of axonal loss in leg nerves. However, a substantial number (approximately one-third) of electrophysiological abnormalities were found in nerves innervating non-weakened muscles. These results imply that in MMN, conduction block is most likely to be found in long arm nerves innervating weakened muscles, but if conduction block cannot be detected in these nerves, the electrophysiological examination should be extended to other arm nerves including those innervating non-weakened muscles.
多灶性运动神经病（MMN）的特征是肢体进行性、不对称无力，无感觉丧失。上肢通常比下肢受累更严重，远端肌肉比近端肌肉受累更明显。MMN中电生理异常的分布及其与肌无力肌群的相关性尚未得到系统研究。本研究的目的是评估电生理异常是有优先分布还是随机分布，神经中的电生理异常是否与所支配肌肉的无力相关，以及这些结果是否与最佳电诊断方案的制定相关。我们比较了39例下运动神经元综合征且对静脉注射免疫球蛋白有阳性反应的患者的肌无力模式和电生理异常情况。所有患者均接受了广泛的标准化电生理检查。脱髓鞘的电生理证据在臂神经中更常见，且随机分布于前臂、上臂和肩部节段。轴突丢失的电生理证据在较长神经中更频繁出现，最常发生在腿部神经。对于臂神经，轴突丢失的长度依赖性可能是由于脱髓鞘病变的随机分布导致轴突变性。肌无力与臂神经中的脱髓鞘和轴突丢失特征相关，与腿部神经中的轴突丢失特征相关。然而，在支配未减弱肌肉的神经中发现了相当数量（约三分之一）的电生理异常。这些结果表明，在MMN中，传导阻滞最可能出现在支配减弱肌肉的长臂神经中，但如果在这些神经中未检测到传导阻滞，则电生理检查应扩展到其他臂神经，包括支配未减弱肌肉的神经。
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